Bottom Bracket 73 or 68

[Etienne]

... I've got a stronglight crank on my Raven Tour.   Seems that I need a 118 squared.   
But very often I found that's related to a 68mm  Bottom Bracket.

On my other Thorn RST or Enduro .... I have another other crank.... Thus my BB stock is over !

All the frame are 73.   But on SJS bike we found Thorn RST equiped with a 68mm BB.

QUESTION : Can I fit a 68mm on a 73 frame ? Is this Reasonnable ?

[Danneaux]

Hi Etienne!

I think we'll need the Official word from Dave, but in all circumstances I can imagine, you need to match the BB width to the shell width.

Looking carefully at the SJSC site, I see this 68mm EBB insert is for the Raven Tour / Mk1 Sport Tour Only:
http://www.sjscycles.co.uk/eccentric-bottom-bracket-insert-fits-raven-tour-mk1-sport-tour-only-prod11656/
This one has some notches in the left side for adjustment.

Looking a bit further, SJSC list this 73mm model for the Raven Mk2 Sport Tour / Catalyst / Enduro / Sterling / Twin Tandem:
http://www.sjscycles.co.uk/eccentric-bottom-bracket-insert-fits-raven-mk2-sport-tour-catalyst-enduro-sterling-twin-tandem-prod9053/
This one has two holes in the left side for a pin wrench to rotate the EBB.

Which insert looks most like yours? If the bike's BB shell is 73mm, then surely the EBB must match. If the shell is 73mm and the EBB is 73, then I'd think you'd need a 73mm square-taper internal BB.

Looking at the SJSC catalog, the only BB I see currently on offer close to 73x118 is this one:
• Royce Titanium Bottom Bracket with 73 mm Shell, £159.99 http://www.sjscycles.co.uk/royce-titanium-bottom-bracket-with-73-mm-shell-red-all-weather-seals-and-stainless-royce-crank-bolts-119-mm-prod13261/

I do know Shimano (UN54 and UN55) make them. Perhaps SJSC is just low on stock at the moment. I'd suggest giving them a call to check on availability and to ask for advice.

Hope this helps.

Best,

Dan.

[il padrone]

Which insert looks most like yours? If the bike's BB shell is 73mm, then surely the EBB must match. If the shell is 73mm and the EBB is 73, then I'd think you'd need a 73mm square-taper internal BB.

Looking at the SJSC catalog, the only BB I see currently on offer close to 73x118 is this one:
• Royce Titanium Bottom Bracket with 73 mm Shell, £159.99 http://www.sjscycles.co.uk/royce-titanium-bottom-bracket-with-73-mm-shell-red-all-weather-seals-and-stainless-royce-crank-bolts-119-mm-prod13261/

When I built up my Nomad I faced a similar problem. I even looked at this Royce model, but the price was a big deterrent. I finished up making a calculated decision to go against orthodoxy.

On the workshop shelf I had a perfectly good, slightly-used 68mm UN-72 BB. I looked at other BBs and saw that the left hand cup normally protruded about 2mm from the shell. The EBB came with the frame so it was 73mm. The 68mm BB would thus sit ~3mm inside the EBB. I fitted it up and it all ran very well. I think it had a 122mm axle and I needed to place the chain-ring on the inside to get correct chain-line. The left hand crank is nice and close to the frame (but not too close). The BB has been fitted for 2 years now with no noticeable problems.

Unorthodox but it works.

[Andre Jute]

http://www.sjscycles.co.uk/eccentric-bottom-bracket-insert-fits-raven-mk2-sport-tour-catalyst-enduro-sterling-twin-tandem-prod9053/

Ooh, that's a verrah nice bottom bracket. Over the top, sure, but you'll never need a new one.

The Shimano UN55 line has a 118mm in 73mm length. If SJS is out of the recommended BB, this might serve:
http://www.chainreactioncycles.com/SearchResults.aspx?Search=Un55
I bought the Shimano because the carriage on my fave Kinex would have killed the attraction of its very low price; can't give you a report because I have only 1700km on it.

Andre Jute

[Etienne]

Tks falks ,,,,  

indeed I need  >>>>>(Danneaux's words) a 68mm EBB insert is for the Raven Tour / Mk1 Sport Tour Only:
http://www.sjscycles.co.uk/eccentric-bottom-bracket-insert-fits-raven-tour-mk1-sport-tour-only-prod11656/

because my frame is 58 mm(not 68 or 73) for the Raven Tour (first version ?) and the frame of the ENDURO and RST is 73.

MARVELLOUS it will fit .... But impossible to take out the old UN55  (BSA to loose via the front)  !! I need to order a new one !